An automated vision-based method for rapid 3D energy performance modeling of existing buildings using thermal and digital imagery

Rapid energy modeling is a streamlined process to capture, model, and analyze building energy performance. Timely assessment of existing building energy performance helps owners and facility managers to identify potential areas for better retrofit, and meet environmental and economic goals. Despite the increasing attention to building energy performance, the current process of energy data collection and modeling is time-consuming and requires certain level of expertise. In order to facilitate the process, this paper presents a new approach for actual energy performance modeling of existing buildings using digital and thermal imagery. First, using an image-based 3D reconstruction pipeline which consists of Structure-fromMotion, Multi-View Stereo, and Voxel Coloring/Labeling, the current geometrical condition of a building is captured. Subsequently, using a new 3D thermal modeling algorithm, a dense thermal point cloud model of the existing building is reconstructed in 3D. Finally, the reconstructed 3D building and thermal models are automatically superimposed within a single environment. Within the resulting 3D spatio-thermal point cloud model, temperature values can be queried and visualized at point level. The proposed method is validated on several rooms in an existing instructional facility. The underlying modeling process, and the potential benefits from converting digital and thermal imagery into ubiquitous sensors and reporters of building energy use are discussed in detail. INTRODUCTION The building sector uses about 40 percent of the total energy produced in the United States (DOE 2010). When looking at the life-cycle energy consumption of the U.S. buildings, nearly three quarters of produced electricity is consumed in operating buildings (DOE 2010). According to a recent report by the Energy Information Administration (EIA 2010), between 2010 and 2030, the increase in building sector’s energy consumption (7.16 Quadrillion Btu) will be more than those of the industrial and transportation sectors (4.05 and 3.36 Quadrillion Btu respectively). This energy is mainly produced from burning fossil fuels, making the building sector to be the largest producer of Greenhouse Gas emissions and the prime leading contributor to anthropogenic climate change (EIA 2010; Architecture203